1. Field of the Invention
The present invention relates to tracking personnel and equipment in hazardous environments, such as underground mines, foundries, mills, large ships, refineries, heavy industry environments, etc., where tracking systems based on GPS (global positioning system) and other technologies are inoperable or do not function.
2. Description of Prior Art
Prior art systems and methods for tracking personnel and equipment in hazardous environments having poor radio signal propagation characteristics lack desired “granularity” (i.e., precision) in determining the location of the personnel and equipment in the hazardous environment.
Additionally, prior art systems may use tracking tags that are not permanently assigned to a particular person or piece of equipment, creating an issue with the accuracy and confidence in identification of the actual person or piece of equipment associated with a particular tracking tag.
Further, since hazardous environments can be “explosive” environments, the tracking system components could be an ignition source if not properly designed.
Some hazardous environments, such as underground mines, can cover miles of territory and may have power and communication taps only every 3,000 to 5,000 feet, typically corresponding to belt heads. Prior tracking systems that relied on power and communication taps were limited to the physical availability of such utilities, however, it is desired to know where personnel and equipment are with more granularity, such as within 1,000 feet or less.
In another example, in a mill environment, particularly an aluminum mill, a fire suppression system may need to be deployed in a basement or other enclosed structure. Deployment of the fire suppression system may create a condition where the basement or other enclosed structure does not contain enough oxygen to support life. In this scenario, it is desired to verify that all personnel have exited from the structure before deployment of the fire suppression system. Because of the enclosed structure, GPS-based systems do not reliably function.
In yet another example, a refinery having overhead pipes and tanks may create an environment where GPS signals cannot be reliably received.
In a still further example, a large ship may include a large enclosed area below deck where tracking of personnel is desired, such as for verification that all personnel have abandoned ship, but where GPS signals cannot be reliably received.